This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. To ultrasound image the hearts of mice exposed to hypobaric (altitude up to 24000ft) conditions for up to 14 days in duration. To start, we would like to do 12 mice at 0, 7, and 14 days. The purpose of our project is to measure the effect of environmental stressors on cardiac function in the mouse. Our stresses include one hour of 500ppm carbon monoxide (CO) and hypoxia, initially in wild type mice, and eventually in eNOS gene knockout mice. Our hypothesis is that the two physiological gases play complementary roles in cardiac mitochondrial biogenesis that are different from hypoxia and have implication for the functioning mouse heart.